Grape and Almond Frangipane Tart

Ingredients

• Pastry dough
• 1 cup whole blanched almonds, toasted and cooled completely
• 1/2 cup sugar, divided
• 1/4 cup all-purpose flour
• 1/8 teaspoon salt
• 3/4 stick unsalted butter, softened
• 2 large eggs
• 1 teaspoon pure vanilla extract
• 1/2 teaspoon pure almond extract
• 2 cups seedless red grapes (3/4 pound), halved
• 1/3 cup sliced almonds (preferably with skin)
• Confectioners sugar for dusting
• Equipment: an 11- by 8-inch rectangular tart pan with a removable bottom (see cooks' note, below); pie weights or dried beans

Directions

1. Preheat oven to 375°F with rack in middle. Roll out dough on a lightly floured surface with a lightly floured rolling pin into a 12-by 10-inch rectangle. Fit dough into tart pan, letting excess hang over edge. Fold overhang inward and press against side of pan to reinforce edge. Lightly prick bottom all over with a fork. Chill until firm, about 30 minutes (or freeze 10 minutes).
2. Line shell with foil and fill with pie weights. Bake until sides are set and edges are pale golden, 20 to 25 minutes.
3. Carefully remove foil and weights and bake shell until deep golden all over, 15 to 20 minutes more. Cool completely. Leave oven on.
4. Pulse whole almonds with 1/4 cup sugar in a food processor until finely ground. Add flour and salt and pulse to combine.
5. Beat together butter and remaining 1/4 cup sugar with an electric mixer until pale and fluffy. Add eggs 1 at a time, beating well after each addition, then beat in extracts. With mixer at low speed, mix in almond mixture until just combined.
6. Spread filling evenly in tart shell and scatter grapes over it, lightly pressing them in. Sprinkle sliced almonds around grapes. Bake until filling is puffed and golden-brown, 35 to 40 minutes. While still hot, dust tart with confectioners sugar, then cool completely.